#include "mystdio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>

#define FILE_MODE 0666

//"w","a",r
_FILE* _fopen(const char* filename, const char* flag)
{
    assert(filename);
    assert(flag);
    int f = 0;
    int fd = -1;
    if(strcmp(flag, "w") == 0)
    {
        f = (O_WRONLY|O_CREAT|O_TRUNC);
        fd = open(filename, f, FILE_MODE);
    }
    else if(strcmp(flag, "a") == 0) 
   {
        f = (O_WRONLY|O_CREAT|O_APPEND);
        fd = open(filename, f, FILE_MODE);
    }
    else if(strcmp(flag, "r") == 0) 
    {
        f = O_RDONLY;
        fd = open(filename, f);
    }
    else
    {
        return NULL;
    }
    if(fd == -1)
    {
        return NULL;
    }
    _FILE* fp = (_FILE*)malloc(sizeof(_FILE));
    if(fp == NULL)
    {
        return NULL;
    }
    fp->fileno = fd;
    //fp->flag = FLUSH_LINE;
    fp->flag = FLUSH_ALL;
    fp->out_pos = 0;
    return fp;
}
int _fwrite(_FILE* fp, const char* s, int len)
{
    memcpy(&(fp->outbuffer[fp->out_pos]), s, len);
    fp->out_pos += len;
    if(fp->flag&FLUSH_NOW)
    {
        write(fp->fileno, fp->outbuffer, fp->out_pos);
        fp->out_pos = 0;
    }
    else if(fp->flag&FLUSH_LINE)
    {
        if(fp->outbuffer[fp->out_pos-1]=='\n')
        {
            write(fp->fileno, fp->outbuffer, fp->out_pos);
            fp->out_pos = 0;
        }
    }
    else if(fp->flag&FLUSH_ALL)
    {
        if(fp->out_pos == SIZE)
        {
            write(fp->fileno, fp->outbuffer, fp->out_pos);
            fp->out_pos = 0;
        }
    }
    return len;
}
void _fflush(_FILE* fp)
{
    if(fp->out_pos > 0)
    {
        write(fp->fileno, fp->outbuffer, fp->out_pos);
        fp->out_pos = 0;
    }
} 
void _fclose(_FILE* fp)
{
    if(fp == NULL)
    {
        return;
    }
    _fflush(fp);
    close(fp->fileno);
    free(fp);
}
